The battle over who should decide to prosecute sex crimes in the military — lawyers or commanders — has exposed a rift among Senate Democrats on the Armed Services Committee with high stakes for the Pentagon.

The debate that raged earlier this summer looks like it will erupt again early in fall. The stakes are high: sexual assaults in the military are the wound that will not heal and Congress has vowed to address it; the Pentagon says the discipline it needs to fight rest in a commander's supreme authority.

The military dodged a bullet earlier this summer when the committee killed a proposal by Sen. Kirsten Gillibrand, D-N.Y., to strip unit commanders of their authority to prosecute sexual assault cases. Instead, a proposal backed by Sen. Carl Levin, the committee chairman from Michigan, prevailed, allowing commanders to retain the authority to prosecute those cases but, among other changes, stripped them of the authority to toss out convictions in sexual assault cases.

To a one, the service chiefs told the Senate that removing commanders' discretion in sexual assault cases — a crisis by their own admission — would undermine the authority at the heart of military culture. Levin agreed and backed by Sen. Claire McCaskill, the Missouri Democrat, and others, won approval last month of their approach in the defense authorization bill.

The House is also moving to address the issue. Earlier this week, two amendments to the annual defense spending bill sponsored by Rep. Jackie Speier, D-Calif., that would add money for sexual assault and harassment training and care passed on a voice vote.

A Pentagon report released this spring revealed its depth: in 2012 troops suffered 26,000 instances of unwanted sexual contact — from groping to rape. That was a 35 percent increase compared with 2010.

The decision on charging, the jury's composition, and whether a conviction or punishment can stand is controlled by a high-ranking officer who is the defendant's superior. The officer is probably not a lawyer nor a judge, although he or she receives written advice from a military attorney.

The arrangement is a core principle for maintaining order within a fighting unit. The United States inherited it from the British military when the nation was formed in the 18th century. Britain, Canada and other countries have moved away from commanding officer's authority.

Gillibrand, who chairs the committee's personnel panel, refused to back down. The system is broken, she has argued, and commanders have not dealt with the problem.

She vowed to bring her measure before the full Senate. It seemed, at the time, to be a refusal to accept defeat. That no doubt irritated Levin, the longtime chairman who has announced he will retire in 2014, and concerned some at the Pentagon.

Now, Gillibrand's office says she has 44 votes in favor of her approach, including eight Republicans. A vote could come as soon as mid-September.